This section provides background information related to the present disclosure which is not necessarily prior art.
Systems for treating exhaust gas produced by an internal combustion engine to reduce exhaust gas emissions in the form of particulates and/or NOX are generally known. Such exhaust gas “after-treatment” systems may include a selective catalytic reduction (SCR) system for the purpose of reducing the NOX level of the exhaust gas below a specified level.
An SCR system generally includes a catalytic reducing agent, or reagent, in the form of an exhaust treatment fluid that is dosed into the exhaust gas stream produced by the engine before entering an SCR catalyst. The SCR catalyst reacts with the combination of engine exhaust gas and reagent solution in a known manner to reduce the NOX content of the exhaust gas stream.
The reagent is generally held in a storage tank. The tank may include fluid level sensors, temperature sensors, and other components that assist in communicating the reagent to a dosing module that doses the reagent into the exhaust gas stream and returning any unused reagent to the tank. Each of these components should be monitored by an on-board diagnostic (OBD) system so that, if a problem with one of the components occurs, an error may be communicated by the OBD system.